Troubleshooting an unfamiliar machine ...

[Castellen]

Hardware wise, you can reduce the machine to the most simple usable state possible to eliminate expansions causing the problem.

For software, remove all non standard workbench programs (like MCP, MagicMenu, etc) if you're using any and run workbench in it's most basic form.  If you still have problems, it could be hardware.

Find out if the crashes are random, or only happen after a specific sequence of events, or after a certain time.

As mentioned before, reseat all socketed devices on the motherboard.  Remove essential expansions like the CPU board and clean edge connectors and sockets with proper gold contact cleaning spray.

Monitor power supply 5V rails for dropouts or excessive noise.

Flex the motherboard while it's running and see if light mechanical stress causes problems (usually hilighting contact problems).

If possible, try swapping memory modules for known good ones, or continuously run MemCheck (from Aminet) for a few hours to soak test all memory addresses.

Dunno, could be lots of things...  

[Castellen]

Pin 40 isn't too major, but pin 20 is the 5V supply to the CIA if I remember correctly.
If this fails, then you will have major problems.  The system will not function without both CIAs working correctly.

You can get replacement parts from an A500 or A3000 as well.  If you use small pliers to straighten the pin, it'll probably be OK.  Remember to use anti static precautions.

I'd be more concerned about those cheap arsed sockets C= decided to use.  If the device pulls out quite easily, it suggests the socket contacts are weak, and possibly intermittent.

You can remove the socket and solder the IC directly into the board, or replace the socket with a machine pin type, which are far more reliable than those dual wipe ones.

As a last ditch effort, you can solder the ICs into the exsisting sockets.  Just flow solder between the IC legs and socket contacts.